The invention relates to a process for forming a vial, in which the mouth area is formed in an open, heat-softened end of a glass tube, as well as a device and a forming finger for forming a mouth area. Then vials, such as ampules, snap-cap glasses, beaded rim vials, etc. are produced from the formed glass tube end.
These vials or ampules are produced from glass tubes in vial machines, in which many glass tubes are held and rotated around their longitudinal axes and fed step by step to individual forming stations. At the forming stations the mouth area of each vial is also formed by rolling the glass tube end with one or more forming rollers.
Vial machines, forming stations and forming fingers of this type are known from DE-PS 15 96 410, 17 96 100 and 36 13 212. In these machines there is always allocated to a forming station one forming finger which is inserted in a glass tube provided by the vial machine. During rolling of the glass tube end the forming finger is held by forming rollers placed on the forming station for supporting the heat-softened glass from inside up to the end of the formation in the glass tube. The formation can take place at individual forming stations. The vial machine is then stopped at the individual forming stations and only after completed formation again moves on from a station.
In lieu of the aforedescribed stop-and-go operating principle, a continuous production is also possible, in which, e.g., four tool stations circulate on a forming station are, e.g, conveyed on a chain, and thus at a angle of rotation of the carousel move equidistantly with a glass tube that is moved past. At this angle, the tool-holder is stationary relative to the longitudinal axis of the glass tube moving past it. The formation of the mouth area takes place simultaneously with the advancement of the tube by forming rollers carried along by each tool-holder and with a forming finger.
Since in the mouth formation the forming finger is in contact with the heat-softened glass over an extended period, the forming finger has to be produced from a high-grade heat- resistant material, and yet because of the operating conditions a frequent change of the forming finger is necessary, and each time the vial production has to be stopped. Also in using several formation stations, as described in DE-PS 15 96 410, the wear of the forming finger remains relatively large and in this case, in addition, the difficulty occurs that the tool-holders, circulating with the forming finger, all have to be adjusted relative to the longitudinal axis of the respective glass tube provided by the carousel, so that a clean mouth formation is guaranteed. If the adjustment, e.g, because of wear on the chain drive of the tool-holder or on a tool-holder itself is no longer precise, the entire forming station with, e.g., four tool-holders as an entire unit has to be overhauled.